Strap track for strapping machine

ABSTRACT

A strap guide track defines a generally rectangular path from a strapping head about an object strapping location and back to the head and comprises a plurality of straight sections and four arcuate corner sections, each straight section and one corner section including a backing plate and each of the other corner sections including an assembly of interleaved rollers with the plates and rollers all coooperating to define a backing wall, each straight section and the other three corner sections including a pair of jaw-like strap retainers pivotally mounted on opposite sides of the backing wall and movable between retaining and releasing positions, each pair of retainers being urged toward the retaining position by a tensioned spring coupled therebetween at points variably spaced from the pivot axis for varying the bias force; the track has a wide entry portion to accommodate ready strap passage and a tapered exit portion to accurately position the strap in the head.

United States Patent [191' Coleman STRAP TRACK FOR STRAPPING MACHINE [75] Inventor: Bestor P. Coleman, Willow Springs,

[73] Assignee: lnterlake, Inc., Chicago, 111.

[22] Filed: Aug. 17, 1970 [21] Appl. No.: 64,434

Primary ExaminerBilly J. Wilhite Attorney-Prangley, Clayton, Mullin, Dithmar & Vogel [57] ABSTRACT A strap guide track defines a generally rectangular path from a strapping head about an object strapping location and back to the head and comprises a plurality of straight sections and four arcuate corner sections, each straight section and one corner section including a backing plate and each of the other corner sections including an assembly of interleaved rollers with the plates and rollers all coooperating to define a backing wall, each straight section and the other three corner sections including a pair of jaw-like strap retainers pivotally mounted on opposite sides of the backing wall and movable between retaining and releasing positions, each pair of retainers being urged toward the retaining position by a tensioned spring coupled therebctween at points variably spaced from the pivot axis for varying the bias force; the track has a wide entry portion to accommodate ready strap passage and a tapered exit portion to accurately position the strap in the head.

25 Claims, 12 Drawing Figures SHEET 3 BF 5 PATENTEDucr 30 I915 I 5 6 l 5 9 l PAIENTEU OCT 30 I975 SHEET 4 BF 5 STRAP TRACK FOR STRAPPING MACHINE This invention concerns automatic strapping machines for securing binder straps about objects to be bound. More particularly, this invention relates to a strap guide track for use in such an automatic strapping machine.

It is a general object of this invention to provide a strap guide track for an automatic strapping machine, which track provides adjustably biased releasable retaining members for retaining the strap in the track with a variable force.

lt is another general object of this invention to provide a strap track which facilitates free movement of the strap therealong byaccommodating lateral deformation of the strap and by providing means for minimizing the frictional resistance of the track to the pasa binder strap track for guiding a strap around an object to be bound, the track comprising a pair of strap retainers extending substantially about the location where the object to be bound is positioned and movable between retaining positions andreleasing positions, the strap retainers in the retaining positions thereof cooperating to define a path for the associated strap about the location where the object to be bound is positioned, the strap retainers-in the releasing positions thereof accommodating removal of the associated strap from the path, bias means coupled to thestrap retainers for yieldably urging the strap retainers toward the retaining positions thereof with a predetermined force, and means for adjusting the force applied by the bias means to the strap retainers, the associated strap upon tightening about the object to be bound being urged against the strap retainers and overcoming the force of the bias means for moving the strap retainers to the releasing positions thereof and releasing the associated strap from the path.

It is another object of this invention to provide a binder strap track of the type set'forth which includes a supporting frame, a backing wall mounted on the frame and extending substantially about the location where the object to be bound is positioned, the strap retainers being mounted adjacent to the back wall and cooperating therewith to define a path for the associated strap.

It is another object of this invention to provide a binder strap track for guiding a binder strap around an object to be bound, the track comprising a backing wall extending substantially about the location where the object to be bound is positioned, a strap retainer mounted adjacent to the backing wall for movement between a retaining position and a releasing position,

the strap retainer in the retaining position thereof cooperating with the backing wall to define a path for the associated strap about the location where the object to be bound is positioned, the strap retainer in the releasing position thereof accommodating removal'of the associated strap from the path, bias means coupled to the strap retainer for yieldably urging the strap retainer toward the retaining position thereof with a predetermined force, and means for adjusting the force applied by the bias means to the strap retainer, the associated strap upon tightening about the object to be bound being urged against the strap retainer and overcoming the force of the bias means for moving the strap retainer to the releasing position thereof and releasing the associated strap from the path. I

In connection with the foregoing object, it is another object of this invention to provide a binder strap track of the type set forth, wherein the strap retainer is mounted for pivotal movement about an axis and is provided with a plurality of coupling locations thereon respectively disposed at varying distances from the axis, the bias means being coupled to the strap retainer at a selected one of the coupling locations for yieldably urging the strap retainer toward the retaining position thereof with a force determined by the distance of the selected coupling location from the axis. 7

It is another object of this invention to provide a binder strap track for guiding a binder strap around an object to be bound, the track comprising a strap guide defining a path for the associated strap extending substantially about the location where the object to be bound is positioned, the path having a plurality of substantially straight portions interconnected by a plurality of corner portions, a plurality of roller assemblies respectively mounted on the strap guide adjacent to'at least certain corner portions of the path, each of the roller assemblies including a plurality of rollers disposed in the adjacent corner portion of the path and arranged longitudinally therealong, whereby the roller assemblies cooperate with the strap guide for facilitating the movement of the associated strap along the corner portions of the path to prevent jamming of the associated strap therein.

In connection with the foregoing object, it is another object of thisinvention to provide a binder strap track of the type set forth wherein each of the roller assemblies includes a plurality of roller groups disposed in the adjacent corner portions of the path and arranged longitudinally therealong, each of the roller groups including a plurality of spaced-apart rollers mounted for rotation about a common axis extending transversely of the path, the rollers of each roller group being interleaved with the rollers of adjacent roller groups so 'as to provide a substantially continuous backing wall for the associated strap along the adjacent corner portions of the path. I

It is another object of this invention to provide a binder strap track of the type set forth wherein the strap guide comprises a plurality of interconnected backing wall sections and a plurality of interconnected strap retainer sections cooperating to form the backing wall and strap retainer of the type set forth.

Still another object of this invention is to provide a binder strap track for guiding a binder strap from a strapping head around an object to be bound and back to the head, the track comprising a backing wall extending substantially about the location where the object to be bound is positioned, a strap retainer mounted adjacent to the backing wall and cooperating therewith for defining a path for the associated strap about the location where the object to be bound is positioned, the backing wall and the strap retainer being dimensioned and arranged to define an entry portion of the path extending from the associated head partly around the object to be bound and having a width substantially greater than the width of the associated strap, the backsubstantially equal to the width of the entry portion and having a width adjacent to the associated head only slightly greater than the width of the associated strap, whereby the entry portion of the path accommodates lateral deformation of the associated strap therein while the exit portion of the path positively and accurately positions the associated strap in the associated head.

In connection with the foregoing object, it is another object of this invention to provide a binder strap track of the type set forth, wherein the strap retainer is mounted for movement between a retaining position and a releasing position and is adjustably biased into the retaining position thereof by a bias means of the type set forth.

In connection with the foregoing object, it is another object of this invention to provide a binder strap track of the type set forth wherein the backing wall and the strap retainer each comprises a plurality of interconnected straight sections and corner sections, each of at least certain of the corner sections being provided with a roller assembly of the type set forth.

Further features of the invention pertain to the particular arrangement of the parts of the binder strap track whereby the above-outlined and additional operating features thereof are attained.

The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood with reference to the following specification taken in connection with the accompanying drawings, in which:

FIG. 1 is a side elevational view of an automatic strapping machine utilizing a binder strap track according to the present invention;

FIG. 2 is an end elevational view of the automatic strapping machine of FIG. 1 as viewed from the righthand side of the FIG. 1;

FIG. 3 is a side elevational view of the binder strap track of the strapping machine of FIG. 1;

FIG. 4 is an enlarged fragmentary side elevational view in partial section of the lower right-hand corner section of the binder strap track of FIG. 3;

FIG. 5 is a top plan view of the portion of the binder strap track illustrated in FIG. 4;

FIG. 6 is a further enlarged fragmentary view of a portion of the roller assembly of the corner portion of the binder strap track illustrated in FIG. 5;

FIG. 7 is a fragmentary shortened side elevational view, on an enlarged scale of the straight bottom flight of the binder strap track illustrated in FIG. 3, with portions of the track assembly broken away;

FIG. 8 is a top plan view of the portion of the binder strap track illustrated in FIG. 7;

FIG. 9 is a further enlarged fragmentary view in partial section of one of the straight horizontal flights of the binder strap track illustrated in FIG. 3, with the strap retainers being shown in the retaining positions thereof;

FIG. 10 is a view in vertical section of the binder strap track of this invention taken along the line l010 in FIG. 9;

FIG. 11 is a view in vertical section of the binder strap track of this invention taken along the line 11-11 in FIG. 9 and illustrating two alternative positions for the bias spring, and

FIG. 12 is a view in vertical section like FIG. 11, but showing the strap retainers in the releasing positions thereof.

Referring now to the drawings, and in particular to FIGS. 1 and 2 thereof, there is shown an automatic strapping machine, generally designated by the numeral 50 and comprising a framework supporting thereon a strapping head assembly and a track assembly 100, the strapping head assembly 70 feeding a length of strap 90 from a supply (not shown) into and along the track 100 and back to the head assembly 70 for binding the strap 90 about an object to be bound. The framework 60 is formed of a series of interconnected tubular pipe sections arranged in a pair of identical and parallel upright halves, the framework 60 including a pair of front upstanding bottom posts 61 and a pair of upright rear bottom posts 62, and a pair of hori-gontally extending bottom beams 63 respectively extending between the upper ends of the front bottom posts 61 and rear bottom posts 62. Each of the beams 63 is formed of a plurality of straight pipe sections 64 interconnected by tee couplers 65, each of the beams 63 being coupled at one end thereof to the upper end of the associated one of the front bottom posts 61 by an elbow 66 and being coupled at the other end thereof to the upper end of the associated one of the rear bottom posts 62 by a tee coupler 67. Each pair of bottom posts 61 and 62 are coupled together at the bottom ends thereof by a generally L-shaped-base plate 68 for providing a firm footing for the framework 60 on the floor or other supporting surface.

Extending upwardly from the tee couplers 67, re-

spectively in vertical alignment with the rear bottom posts 62, are a pair of rear top posts 69, the posts 62 and 69 cooperating to form continuous upstanding rear posts for the framework 60. Mounted upon the front ends of the beams 63 and extending therebetween is a mounting platform 71 which supports thereon the head assembly 70. Extending vertically upwardly from the upper end of the head assembly 70 in vertical alignment with the beams 63 are a pair of front top posts 72. Extending horizontally from the front top posts 72 to the rear top posts 69 are a pair of upper beams 73, each of the beams 73 being coupled at the opposite ends thereof to the upper ends of the associated ones of the front top posts 72 and rear top posts 69, respectively by elbows 74. Two pairs of object or package support rollers 75 are respectively mounted a short distance above the bottom beams 63 substantially in vertical alignment therewith, each pair of rollers 75 being axially aligned end-to-end parallel to the adjacent one of the beams 63 and having axles 76 at the opposite ends thereof respectively journaled in bearings 77, the bearings 77 being mounted on vertical support members 78 respectively coupled to the tee couplers 65 of the associated beam 63. It will be noted that the posts 69 and 72 and the beams 63 and 73 of the framework 60 define a generally rectangular opening or strapping location for accommodating therein an object or package 80 supported on the rollers 75 for being bound by the strapping machine 50.

The head assembly 70- is provided at the forward lower end thereof with a strapping input chute 79 into which the leading end of a binder strap is fed from an associated supply roll (not shown). The leading end of the strap 90 is then engaged and moved by a feed wheel 81 into the entry end of the track assembly 100,

as indicated in FIG. 3. The track assembly 100 may have any desired shape, but is preferably generally rectangular in shape and has dimensions substantially similar to the dimensions of the rectangular upper portion of the framework 60. More particularly, the track 100 comprises four straight flights including a front vertically extending flight 101, a top horizontally extending flight 102, a rear vertically extending flight 103 and a bottom horizontally extending flight 104, the straight flights 101 to 104 being respectively interconnected by four arcuate corner flights including a top front corner flight 106, a top rear corner flight 107, a bottom rear corner flight 108 and a bottom front corner flight 109. The track 100 defines a generally rectangular path 105 for the strap 90 about the strapping location 85 as will be explained more fully below. Each of the straight flights 101 to 104 is made up on one or more straight track sections, generally designated by the numeral 110. In the embodiment illustrated in FIG. 3, the front flight 101 comprises one section 110, the top and bottom flights 102 and 104 each comprise three straight sections 110, and the rear flight 103 comprises two straight sections 110. It will, of course, be recognized that any other number of straight sections 110 may be utilized in the various straight flights of the track 100 depending upon the size and geometry of track desired. The straight sections 110 are all identically constructed, whereby only one of the straight sections 110 will be described in detail.

First, by way of definition, the space surrounded by the track 100 will hereinafter be referred to as being disposed inwardly of the track, while the space disposed outside the perimeter of the track will be considered as being disposed outwardly of the track. Referring now to FIGS. 7 to 11 of the drawings, it will be seen that the straight section 110 comprises backing member 111, coupled by a coupling bracket 120 to a mounting bracket 130 which is supported from the framework 60, the straight section 110 further including a pair of retaining members 140 coupled together by a bias assembly 150. More particularly, the backing member 111 is in the form of a generally L-shaped site'sides of the inner leg 122 transversely of the track 100 are a pair of wing-like arms 124, having the outer ends thereof curved outwardly of the track 100. Each of the arms 124 is provided at the outer extremity thereof with a stop tab 125 projecting forwardly therefrom longitudinally of the track 100. The outer leg 123 of the coupling bracket 120 is secured by means of a mounting screw or bolt 128 to a mounting bracket 130. The mounting bracket 130 is generally U-shaped and includes a bight portion 131 disposed in engagement with the outer surface of the coupling bracket leg 123 and secured thereto by the screw or bolt 128. Diverging outwardly from the sides of the bight portion 131, integral therewith and extending inwardly of the track 100 on opposite sides thereof, are a pair of legs 132 respectively terminating in curled foot portions 133 which are respectively looped around the adjacent ones of the beams or posts of the framework 60, as is best illustrated in FIGS. 1 and 2. Preferably, the foot portions 133 are secured to the framework 60 by suitable fasteners (not shown). Thus, as is best shown in FIG. 1, it will be noted that the track 100 is disposed slightly outwardly. of the framework 60 and has a perimeter I slightly greater than the framework 60. Also, as is apright-angle plate having a short leg 112 integral at one end thereof with anddisposed substantially normal to an elongated leg 113, the leg 113 extending longitudinally of the track 100 and terminating in a distal end 114. The backing member 111 is so arranged that the short leg 112 thereof extends outwardly of the rectangular track 100, with the inwardly facing surface 115 of the elongated arm 1 13 forming a backing wall for the associated binder strap 90, as will be explained in'more therefrom substantially normal thereto in a direction longitudinally of the track 100. The bight portion 121 of the coupling bracket 120 is secured to the short leg 112 of the backing member 11 1 by a pair of mounting screws or bolts 126. The inner leg 122 of the coupling bracket 120 is connected by'suitable meansto the distal end 114 of the next adjacent backing member 111. Integral withand extending outwardly from the oppoparent from FIG. 2, it will be noted that the track is disposed in use between the two upright halves of the framework 60.

Respectively disposed along opposite side edges of the backing member 111 are a pair of strap retainers, generally designated by the numeral 140. The retainers 140 are mirror images of each other and each comprises a generally L-shaped member having a side plate 141 extending generally outwardly of the track 100 along the adjacent side edge of the backing member 111 and a cover plate 142 integral with the side plate 141 at the inner end thereof and extending substantially normal thereto transversely of the track 100. The retainers 140 are so arranged that the cover plates 142 thereof are disposed toward each other and are spaced a slight distance inwardly of the backing surface of the backing member 111. The retainers are some-- what longer than the backing member 111, and each terminates in a leading end 143 and a trailing end 144. The trailing ends 144 of the plates 141 are slightly wider than the leading ends 143 thereof, whereby the side plates 141 are tapered slightly from the trailing ends 144 to the leading ends 143 thereof. This tapered construction of the retainers 140 permits them to be overlapped along the track 100, with the leading ends 143 of each pair of retainers 140 being received within the trailing ends 144 of the retainers 140 of the adjacent straight section 110. In order to facilitate this overlapping arrangement of the retainers 140, the leading and trailing ends 143 and 144 of the cover plates 142 are each provided with edges l-45tapered inwardly transversely of the track, as is best illustrated in FIGS. 5 and 8.

Referringnow to FIGS. 9 to 12 of the drawings, two adjacent straight sections 110 have been shown to illustrate this overlapping arrangement, with the retainers 140 associated with the forward section 110 (to left in FIG. 9) being designated by the letter A, while the retainers 140 associated with the rearward section 110 are designated by the letter B. Formed in the leading edge of each of the side plates 141 and extending rearwardly thereof longitudinally of the track is a generally rectangular slot 146 shaped complementary to the arms 124 on the coupling bracket120 associated with the adjacent straight section 110. Similarly, the trailing edge of each of the side plates 141 has formed therein a slot 147 extending forwardly thereof longitudinally of the track 100 and shaped complementary to the arms 124 of the associated coupling bracket 120. In use, the retainers 140 are assembled with the arms 124 of the associated coupling bracket 120 being respectively received in the slots 147 of the associated retainers 140, and with the arms 124 of the coupling bracket 120 associated with the straight section 110 adjacent to the leading end of .the retainers 140 being received in the slots 146 thereof, all as is clearly illustrated in FIGS. 7, 8 and 10 of the drawings. Thus, referring to FIG. 10, the arms 124 of the coupling bracket 120 are disposed through both the rear slots 147A of retainers 140A and the front slots 1468 of retainers 140B. In this manner, the overlapping retainers 140A and 1408 are securely held in position longitudinally of the track 100, with longitudinal movement of the retainers 140 being limited by the arms 124 of the adjacent coupling brackets 120.

The dimensions of the retainers 140 and the associated coupling brackets 120 are such that the retainers 140 are positively, yet loosely held in position in the track 100 to accommodate lateral movements of the retainers 140 between retaining positions illustrated in FIGS. 7 through 11 of the drawings and releasing positions illustrated in FIG.*12 of the drawings. The retainers 140 in their retaining positions, are so arranged that the side plates 141 thereof are disposed substantially normal to the backing wall 115 of the backing member 111, while the cover plates 142 are disposed substantially parallel to the backing wall 115 and extend toward each other with the inner edges thereof being separated by a very slight distance substantially smaller than the width of the associated strap 90. In order to accommodate the overlapping arrangement thereof, the retainers 140 are disposed slightly closer together at the leading ends 143 thereof than at the trailing ends 144 thereof, as indicated in FIG. 8. As is clearly illustrated in FIGS. 9 to 11 of the drawings the retainers 140, in the retaining position thereof, cooperate with the backing wall 115 to define the path 105 for the associated strap 90. i 1

Preferably, the path 105 so defined is generally rectangular in transverse cross section, having a depth between the backing surface 115 and the retainer cover plates 142 slightly greater than the thickness of the associated strap 90 to accommodate free-passage of the strap 90 longitudinally along the path 105, while maintaining a positive guidance for the strap 90. The width of the path 105 between the retainer side plates 141 is preferably substantially greater than the width of the associated strap 90, in order to accommodate the sidewise or lateral deformation or camber of the strap 90 which may result from non-uniform internal stresses therein, particularly in straps made of synthetic material such as plastics. Without the provision of this additional path width, the sidewise camber of the strap 90 would cause the strap 9 0-to bind against the retainer side plates 141 resulting in unduly high friction and consequent jamming of the strap 90 in the path 105. It will, of course, be appreciated that the wide track path will also accommodate a wider strap having the or no camber, for example, steel strap. In a preferred embodiment of the invention, the path 105 has a width of approximately 1 k inches and is usuable with straps having widths in the range of from about inch to about inch. It will be understood, however, that there is no limit to the width of the path which may be utilized in this invention.

. The retainers 140 are pivotally movable about the outer edges of the side plates 141 to the releasing positions thereof, illustrated in FIG. 12 of the drawings, wherein the inner edges of the cover plates 142 are spaced apart a distance greater than the width of the strap 90. The retainers 140 are guided in this pivotal movement between the retaining and releasing positions thereof by the arms 124 of the. associated coupling brackets 120. As is apparent from FIG. 10, the slots 146 and 147 at the leading and trailing ends of the retainers 140, cooperate with the curved arms 124 of the coupling brackets to guide the retainers 140 in a generally arcuate path. This pivotal movement of the retainers 140 away from each other to the releasing positions thereof is limited by the stop tabs on the arms 124 of the coupling brackets 120. When the retainers have reached their releasing positions, the outer surfaces of the side plates 141 will bear against the stop tabs 125 to prevent further outward movement of the retainers 140.

In order to control the movement of the retainers 140 between the retaining and releasing positions thereof, there is provided in each of the straight sections 110 a bias assembly, generally designated by the numeral 150. As a part of this bias assembly each of the retainer side plates 141 is provided centrally thereof with a plurality of openings therethrough including a relatively large circular opening 151 surrounded by a plurality of relatively small circular openings 152, the openings 152 being arranged in a substantially circular pattern about the large opening 151 and preferably being four in number. A tension spring 153 is disposed between the side plates 141 and outwardly of the leg 113 of the backing member 111, the tension spring 153 being provided at the opposite ends thereof with coupling hooks 154. In use, each of the coupling hooks 154 is disposed in a selected combination of the openings 151 and 152 of the adjacent side plate 141 for coupling the spring 153 to the retainers 140. More particularly, the hooks 154 may be fed out through the large opening 151 and back through one of the small openings 152, or vice versa, as is indicated in FIGS. 9 and 11 of the drawings. As is apparent from the drawings, the tension spring 153 will urge the retainers 140 toward each other and, thus, into the retaining positions thereof illustrated in the drawings. It will be noted that, preferably, each of the openings 151 and 152 is disposed inwardly of the pivot axis (disposed at the outer edges of the side plates 141) about which the retainers 140 pivot between the retaining and releasing positions thereof. Thus, the tension spring 153 will serve to urge the retainers 140 toward each other and into the retaining positions thereof.

It is an important feature of bias assembly that it permits an adjustment of the force with which the retainers 140 are urged into their retaining positions.

More particularly, it will be apparent that by changing the position at which the tension spring 153 is coupled to the retainers 140, by moving the hooks 154 to a different combination of openings 151 and 152, the leverage achieved by the tension spring 153 can be altered. Thus, when the tension spring 153 is in the lowermost position thereof indicated in solid lines in FIGS. 9 to 11, it will be disposed very close to the pivot axis of the retainers 140 and will, therefore, have minimum effect and will urge the cover plates 142 together with a minimum force. However, if tension spring 153 is moved to the innermost position, illustratedin phantom in FIG. 11, it will be located the farthest possible distance from the pivot axis of the retainers 140, whereby the cover plates 142 will be urged together with a maximum force. It will be-apparent that movement of the tension spring 153 to intermediate positions will achieve intermediate biasing forces and, while only four coupling positions or locations have been provided in the preferred embodiment, it will of course be observed that any desired number may be provided.

The corner flight 109 of the track 100 disposed at the lower left-hand corner of the track, as illustrated in FIGS. 3 and 7, comprises a corner section 155 which includes an arcuate backing member 156, and a pair of side plates 159. The backing member 156 is similar in construction to the backing members 111 of the straight sections 1 10, and includes a short mounting leg 1 57 and an elongated arcuate leg 158. The backing member 156 is coupled to the adjacent straight section 110 in the same manner as was described above with respect to the backing members 111, the only difference between the backing member 156 and the backing members 111 being that the elongated leg 158 of the backing member 156 is arcuate and defines the adjacent corner portion of the path .105. The side plates- 159 are each arcuate and shaped complementary to the elongated leg 158 and are coupled thereto on opposite sides thereof by suitable means (not shown). The side plates 159 are preferably disposed parallel to each other and substantially normal to the backing member leg 158, with the inner edges of the side plates 159 extending inwardly a short distance beyond the inner surface of the backing member leg 158, so as to cooperate therewith to define a trough or channel portion of the path 105. The leading end of the corner section 155 extends into the head assembly 70 for feeding the leading end of the associated strap 90 thereinto in a wellknown manner.

Each of the other corner flights 106, 107 and 108 of the track 100 comprises a corner section, generally designated by the numeral 160. The corner sections 160 are all identical to one another, whereby only one of the corner sections 160 will be described in detail. Each of the comer sections 160 includes a pair of generally arcuate side plates 161 disposed parallel to each other at opposite side edges of the track 100. Each of the side plates 161 has an arcuate inner edge 162 and is provided with an outwardly flared trailing end 163, the inner edge 162 being recessed at the leading end thereof to define a short, generally rectangular tongue portion 164. In use, the outwardly flared trailing ends 163 are disposed closely adjacent to the leading end of one adjacent straight section 110 while the tongues 164 are inserted in the trailing end of the other adjacent straight section 110. For this purpose, the tongues 164 may be provided with slots (not shown) for accommodating the arms 124 of the adjacent coupling bracket 120. Each of the side plates 162 is provided along the outer edge thereof with a centrally located out-turned flange 165 having a gap 166 therein, for a purpose to be described more fully hereinafter. Disposed between the side plates 161 substantially parallel thereto are a plurality of roller support plates 167, shaped complementary to the side plates 161 and secured thereto by suitable means such as spacer bars (not shown) mounted by suitable fasteners 169. Each of the roller support plates'167 has an arcuate inner edge shaped complementary to the inner edge 162 of the side plates 161 and spaced outwardly a slight distance therefrom. Preferably, six of the support plates 167 are provided, with two of the plates 167 being disposed back-to-back against the inner surface of each of the side plates 161, and the other two support plates 167 being spaced apart approximately midway between the side plates 161, as is clearly illustrated in FIG. 6, for purposes to be described in greater detail hereinafter.

Disposed between the side plates 161 at the trailing end thereof is an entry spacer 170 secured to the side plates 161 by suitable fasteners such as screws or bolts 171. The spacer 170 is provided at the trailing end thereof with a lip 172 which extends rearwardly beyond the trailing ends of the side plates 161 and extends a shortdistance into the adjacent straight section 110, terminating closely adjacent to the distal end 1140f the adjacent backing member 111. The spacer 170 and the lip 172 thereof have a flat inner surface which forms a continuation or extension of the backing wall of the adjacent straight section 110 for guiding the associated strap 90 into the corner section 160. Disposed between the inner two of the mounting plates 167 at the trailing end thereof is a mounting block 173, secured to the support plates 167 by a screw or bolt 174. Extending outwardly from the mounting block 173 is a cylindrical spacer 175 which terminates at the inner surface of the bight 131 of the mounting bracket 130, the corner section being coupled to the mounting bracket 130 by a fastener 176 which extends through a complementary opening in the bight portion 131 of the mounting bracket 130, through the spacer and into the mounting block 173. Disposed between the side plates 161 adjacent to the leading end thereof, is an exit spacer 177 which is provided with a pair of side arms 178 respectively secured to the side plates161 by mounting screws of bolts 178a. Connected to the inner ends of the side arms 178 is an exit plate 179 extending forwardly into the trailing end of the adjacent straight section 110 and terminating at a point closely adjacent to the trailing end of thefadjacent backing member 1 l 1'. Preferably, the exit plate 179 has a flat inner surface which is substantially coplanar with the backing wall 1 15 of the adjacent backing member 111, whereby the exit plate 179 serves as an extension of the backing wall 115, for guiding the leading end of the associated strap 90 thereonto.

Mounted on the support plates 167 is a roller assembly, generally designated by the numeral 180, and comprising a plurality of roller groups 181. In the preferred embodiment thirteen of the roller groups 181 bridge form a have been disclosed, but it will be observed that inner mounting plates 167. Each of the rollers 182 is provided on one side thereof with a short hub 184 and on the other side thereof with a long hub 184a, respectively joumaled in complementary openings in the support plates 167 for rotational movement about the axis thereof. Preferably, the pairs of rollers 182 are spaced apart on a common axle. The rollers 182 of each of the roller groups are arranged coaxially so that the hubs 184 thereof define a common shaft having an axis extending transversely of the track 100 substantially normal to the side plates 161. The roller groups 181 are so arranged that the rollers 182 thereof are interleaved.

' Referring to FIG. 6, this interleaving is accomplished in a relatively simple manner. More particularly, in one roller group 181 the short hubs 184 are all disposed toward one side of the track 100, while the long hubs 184a are all disposed toward the other side, while in the adjacent roller groups 181 the arrangement is reversed, i.e., the short hubs 184 are all disposed toward the other side of the track while the long hubs 184a are all disposed toward the one side of the track 100. The roller groups 181 are mounted in the corner section 160 so that the axes thereof are spaced apart longitudinally of the path 105 a distance less than the diameter of the rollers 182, whereby the rollers 182 of any one roller group 181 will be interleaved with the rollers 182 of adjacent roller groups 181. Furthermore, the rollers 182 of any one roller group 181 are spaced apart transversely of the track 100 a distance substantially less than the width of the associated strap 90, whereby the plurality of interleaved roller groups 181 combine to form a substantially continuous backing surface for the associated strap 90. The rotational movement of the roller groups 181 accommodates longitudinal movement of the associated strap 90 along the arcuate corner sections 160 with a minimum of friction.

Disposed adjacent to the exit spacer 177 between the side plates 161 is a stripper block 185 secured to the side plates 181 by suitable fasteners 186. The stripper block 185 is provided at the trailing end thereof with a plurality of stripper fingers 187 respectively disposed between the rollers 182 of the leading one of the roller groups 181. Thus, the stripper block 185 and fingers 187 thereof cooperate with the roller assembly 180 and the exit plate 179 to ridge the gap therebetween and form continuous backing surface for the associated strap 90 along the track 100. Preferably, similar stripper fingers (not shown) are provided on the entry spacer 170 to facilitate the passage of the strap 90 from the entry spacer 170 onto the roller assembly 180.

Respectively disposed along the outer surface of the side plates 161 approximately midway between the ends thereof are a pair of strap retainers, generally designated by the numeral 190, each of the retainers 190 including a generally rectangular side plate 191 being provided at the outer edge thereof with a short tab 192 disposed in use in the gap 166 in the side plate flanges 165. The tab 192 may also be provided with an intumed flange (not shown) disposed inwardly of the associated side plate 161 along the outer edge thereof, whereby the tap 192 cooperates with the flange 165 to form a loose hinge for the retainer 190. The side plate 191 is provided at tthe inner end thereof with a pair of wings or extensions 193 respectively extending forwardly and rearwardly thereof longitudinally of the track 100, each of the wings 193 being provided with a side plate 194 substantially coplanar with the side plate 191. Integral with the side plates 191 and 194 along the inner edges thereof is a cover plate 195 extending substantially normal to the side plates 192 and 19d and spaced a slight distance inwardly of the inner edge 162 of the side plates 161. The retainers 190 are so arranged on the corner section 160 that the cover plates 195 thereof are disposed toward one another transversely of the track 100 in substantially the same configuration as was described above with respect to the retaining members 140.

The retainers 190 are adapted for pivotal movement about the tabs 192 thereof between retaining positions and releasing positions. In the retaining positions thereof, illustrated in FIGS. 4 to 6 of the drawings, the side plates 192 are disposed substantially parallel to the side plates 161, while the cover plates 195 are disposed toward each other, being spaced apart along the inner edges thereof a slight distance substantially less than the width of the associated strap 90. In this retaining position the cover plates 195 cooperate with the roller assembly 180 to define the adjacent portion of the path 105. It will be noted that the dimensions of the corner section 160 are such that the lateral dimensions of the portion of the path 105 therein will be substantially the same as the lateral dimensions of the portions of the path 105 defined by the straight sections 110. The retainers 190 are movable about a pivotal axis through the tabs 192 outwardly to a strap releasing position (not shown) wherein the cover plates 195 are separated from one another by a distance greater than the width of the associated strap 90. In order to control this pivotal movement between the retaining and releasing positions thereof, the retainers 190 are provided with bias assemblies essentially similar to the bias assemblies described in connection with the straight sections 110 above. Thus, each of the side plates 191 is provided adjacent to the outer end thereof with a relatively large circular opening 196 therethrough surrounded by a plurality of relatively small openings 197 arranged in a substantially circular pattern about the large opening 196. A tension spring 198 is disposed between the side plates 192 and is coupled thereto by having the ends thereof hooked through selected combinations of the openings 196 and 197 in the same manner as was described above with respect to the bias assembly 150. Thus, the retainer 190 will be urged toward the retaining position thereof by an adjustable bias force.

While, as was described above, the track 100 is dimensioned to provide a path 105 therealong having a width substantially greater than the width of the associated strap 90 to accommodate lateral camber of the strap 90, it will be appreciated that this wide path may hinder the accurate positioning of the leading end of the strap 90 in the head assembly as the strap exits from the track 100. Accordingly, the bottom straight flight 104 of the track and, in particular, the last straight section C thereof, has been provided with gradually tapering lateral dimensions. Referring to FIGS. 7 and 8 of the drawings, it will be seen that the straight section 110C has the backing member 111C and retainers C thereof constructed with a gradually tapered lateral dimension from the trailing end to the leading end thereof. This tapering is of such a degree that, while the width of the path 105 at the trailing end of the straight section 110C is the same as the path width in the other straight sections 110, the width of the path 105 at the leading end of the straight section 110C adjacent to the corner section is only 13 slightly greater than the width of the associated strap 90 for severely limiting the sidewise motion thereof. Similarly, the width of the portion of the path 105 through the corner section 155 is only slightly greater than the width of the associated strap 90, whereby the leading end of the strap 90 may be positively and accurately positioned in the head assembly 70, thereby to facilitate the binding together of the leading and trailing ends of the strap 90 in the head assembly as'is well known to those skilled in the art. While the tapered exit portion of the track 100 occupies only the last straight section 110 of the track 100, it will be appreciated that a longer or shorter tapered portion may be provided if desired. In the preferred embodiment of the invention, the tapered exit portion of the track 100 tapers to a minimum width only slightly greater than the minimum width of strap to be used therewith. The width of the backing members 156 may vary with the width of the strap, the backing member 156 being disposed between the leading ends of the retainers 140C for holding them spaced apart sufficiently to accommodate the strap being used.

The operation of the track 100 will now be described in detail. An object or package 80 which is to be bound is first positioned on the supporting rollers 75 in the strapping location 85 indicated in FIG. 1 of the drawings. When the object 80 is in this location, the track 100 is disposed in surrounding relationship with the object 80 to be bound. Suitable conveyor apparatus may be provided for placing the object 80 onto the supporting roller 75 and for removing it therefrom after the strapping operation has been completed. The binder strap 90 may be of any of several well-known types including steel strap, nylon, polypropylene of paper straps. The strap 90 is fed from a supply roll (not shown) disposed adjacent to thehead assembly 70, the leading end of the supply strap from the supply roll being fed through the chute 79 into the'head assembly 70 and to and around the feed wheel 81. The feed wheel 81 feeds the strap 90 into the entry end of the track 100 as illustrated in FIG. 3 of the drawings. Preferably, the strap 90 will be fed from the bottom of the associated feed roll, so that the naturaltendency of the strap 90 to follow the curvature of the feed roll will hold the leading end of the strap 90 against the backing surface 115 of the track .100 as the leading end of the strap 90 travels along the path 105. The feed wheel 81 will continue feeding the strap 90 into the track 100, driving the strap 90 along the track 100 until the leading end of the strap 90 has returned from the track 100 back into the head assembly 70 and overlaps the trailing end by a predetermined distance, all in a wellknown manner. 1 I

It has been found that when straps having low column strength, such as nylon or polypropylene straps, are used the friction developed in the corner flights 106 to 109 of the track 100% the strap 90 is driven therealong causes the strap 90 to fold or buckle in these corner sections resulting in jamming of the strap 90 therein.

ment of the strap therealong without jamming. It will be noted that roller assemblies 180 have been provided in only the first three of the corners of the track 100, viz., the corner flights 106, 107 and 108. This is because it has been found that the friction in the last corner flight 109 is insufficient to necessitate the use of roller assembli'es therein. As a general rule, the friction in an angular track will be greatest in the first corner encountered by the strap and will be proportionately less in each of the subsequent corners. This is because the prime source of the resistance to the movement of the strap along the track 100 is the weight of the strap itself. Thus, the farther the leading end of the strap travels along the track 100, the greater the length of strap which will be disposed ahead of the first corner flight 106, whereby the resistance of passage of the strap through the corner flight 106 increases as more and w more strap is fed to the track 100. Similarly, but to a This occurs because the column strength of the strap is insufficient to withstand the driving force necessary to overcome this frictional resistance of the track. in order to prevent this jamming when low column strength straps are used, the roller assemblies 180 have been provided in the corner sections 160 of the track 100. Thus, the friction in the corner flights of the track will be vastly reduced, thereby facilitating the movelesser degree, the resistance to passage of the strap through each of the corner flights 107 and 108 will increase gradually as the amount of strap disposed ahead of these respective corner flights increases. Obviously, however, the amount of strap disposed ahead of the corner flights 107 and 108 can never be as great asthat disposed ahead of the corner flight 106, whereby the maximum resistance presented in the corner flights 107 and 108 will be proportionately less than the maximum resistance presented in the first corner flight 106. Since only a very short length of strap will ever'be disposed ahead of the last corner flight 109, very little resistance is built up in this corner and the roller assembly is not required in this corner, although one may be provided if desired. It will be apparent that, if different lengths and shapes of track are utilized, different arrangements of the roller assemblies 180 may be found to be desirable.

Since the track is disposed in a substantially vertical plane, the portion of the strap disposed in the top flight 102 and side flights 101 and 103 will have a tendency to fall from the path 105. However, the strap is retained in the path 105 by the retainers in the retaining positions thereof. When the leading end of the strap 90 has returned to the head assembly 70, the trailing endof the strap will be tightened about'the object to be bound in a well-known manner. This tightening of the strap 90 about the object 80 will cause the strap 90 to bear against the cover plates 142 of the retainers 140 and the cover plates 195 of the retainers 190. As-

the tightening continues, the force on the strap 90 will overcome the bias force of the springs 153 and 198, thereby moving the retainers 140 and to the strap releasing positions thereof. Thus, the strap 90 will be released from the track 100 to be securely tightened about the object 80. After sufficient tension has been achieved in the strap 90, the strap ends will be severed and bound together in a standard manner. Afterwards the bound object 80 is removed from the strapping machine 50 and another object to be bound'is movedinto position on the rollers 75.

It will be seen from the foregoing that there hasbeen described a novel track assembly for an automatic strapping machine, which track assembly is suitable for use with a wide variety of straps including those having low column strength.

More particularly, there has been'provided a binder strap track having strap retainers mounted for movement between retaining and releasing positions, the

strap retainers being biased toward the retaining positions thereof by adjustable bias assemblies by means of which the force urging the retaining members toward their retaining positions may be varied.

In addition, there has been provided a binder strap track shaped and dimensioned to accommodate binder straps having low column strength, the strap path defined by the track having a width substantially greater than the width of the associated strap to accommodate lateral deformation of the strap. in this connection, the track is provided with a tapered exit portion tapering to width only slightly greater than the strap width to permit accurate positioning of the strap in the head assembly. g

Finally, there has been provided a binder strap track having roller assemblies mounted in at least several of the corner sections thereof to minimize the frictional resistance of these corner sections to the passage of the strap therealong.

While there has been described what at present are considered to be the preferred embodiments of the invention, it will be understood that various modifications may be made therein and it is intended to cover in the appended claims all such modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. A binder strap track for guiding a strap around an object to be bound, said track comprising a pair of strap retainers extending substantially about the location where the object to be bound is positioned and movable between retaining positions and releasing positions, said strap retainers in the retaining positions thereof cooperating to define a path for the associated strap about the location where the object to be bound is positioned, said strap retainers in the releasing positions thereof accommodating removal of the associated strap from said path, bias means coupled to said strap retainers for yieldably urging said strap retainers toward the retaining positions thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainers, the associated strap upon tightening about the object to be bound being urged against said strap retainers and overcoming the force of said bias means for moving said strap retainers to the releasing positions thereof and releasing the associated strap from said path.

2. The binder strap track set forth in claim 1, wherein said bias means comprises a spring.

3. The binder strap track set forth in claim 1, wherein said strap retainers are adjustable to be spaced apart in the retaining positions thereof a distance less than the width of the associated strap and in the releasing positions thereof to be spaced apart a distance greater than the width of the associated strap.

4. The binder strap set forth in claim 1, wherein said path is disposed in a substantially vertical plane.

5. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, a strap retainer mounted adjacent to said backing wall for movement between a retaining position and a releasing position, said strap retainer in the retaining position thereof cooperating with said backing wall to define a path for the associated strap about the location where the object to be bound is positioned, said strap retainer in the releasing position thereof accommodating removal of the associated strap from said path, bias means coupled to said strap retainer for yieldably urging said strap retainer toward the retaining position thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainer, the associated strap upon tightening about the object to be bound being urged against said strap retainer and overcoming the force of said bias means for moving said strap retainer to the releasing position thereof and releasing the associated strap from said path.

6. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a backing wall extending substantially about the location where the object to the bound is positioned, a pair of strap retainers respectively mounted adjacent to opposite side edges of said backing wall for movement between retaining positions and releasing positions, said strap retainers in the retaining positions thereof coop-v erating with each other and with said backing wall to define a path for the associated binder strap about the location where the object to be bound is positioned, said strap retainers in the releasing positions thereof accommodating removal of the associated strap from said path, bias means coupled to each of said strap retainers for yieldably urging said strap retainers toward the retaining positions thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainers, the associated strap upon tightening about the object to be bound being urged against said retaining members and overcoming the force of said bias means for moving said strap retainers to the releasing position thereof and releasing the associated strap from said-path.

7. The binder strap set forth in claim 6, wherein each of said strap retainers comprises a generally L-shaped plate having first and second integral flanges disposed substantially normal to each other, said first flanges being disposed substantially normal to said backing wall when said strap retainers are in the retaining positions thereof, said second flanges being disposed substantially parallel to said backing wall and spaced therefrom and extending toward each other when said strap retainers are in the retaining positions thereof.

8. The binder strap track set forth in claim 7, wherein said bias means is coupled to said first flanges.

9. The binder strap track set forth in claim 6, wherein each of said strap retainers comprises a plurality of interconnected sections, the sections of one of said strap retainers corresponding respectively to the sections of the other of said strap retainers to form a plurality of pairs of strap retainer sections, and further including a plurality of bias means respectively coupled to said pairs of strap retainer sections.

10. The binder strap track set forth in claim 9, wherein the ends of each of said strap retainer sections overlap the adjacent ends of adjacent strap retainer sections to accommodate free movement of the associated strap in one direction along said path.

11. A binder strap track for guiding a binder strap around an object to bebound, said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, a strap retainer mounted adjacent to said backing wall for pivotal movement about an axis between a retaining position and a releasing position, said strap retainer in the retaining position thereof cooperating with said backing wall to define a path about the location where the object to be bound is positioned, said strap retainer in the releasing position thereof accommodating removal of the associated strap from said path, said strap retainer being provided with a plurality of coupling locations respectively disposed at varying distances from said axis, bias means coupled to said strap retainer at a selected one of said coupling locations for yieldably urging said strap retainer toward the retaining position thereof with a force determined by the distance of the selected coupling location from said axis, the associated strap upon tightening about the object to be bound being urged against said strap retainer and overcoming the force of said bias means for moving said strap retainer to the releasing position thereof and releasing the associated strap from said path.

12. The binder strap track set forth in claim 11, wherein said bias means-comprises a spring.

13. The binder strap track set forth in claim 11, wherein said strap retainer is provided with an opening therein at each of said coupling locations, said bias means comprising a spring having one end thereof received in a selected one of said openings for engagement with said strap retainer thereat.

14. The binder strap track set forth in claim 11, wherein said coupling locations are arrangedin a generally circular pattern on said strap retainer, said strap retainer being provided with a plurality of first openings therein respectively disposed at said coupling locations and a second opening disposed centrally of said first openings, said bias means comprising a spring having a hook at one end thereof disposed through said second opening and a selected one of said first openings for coupling said spring to said strap" retainer.

15. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a strap guide defining a path for the associated strap extending substantially about the location where the object to be bound is positioned, said path having a plurality of substantially straight portions interconnected by a plurality of corner portions, a plurality of roller assemblies respectively mounted on said strap guide adjacent to at least certain corner portions of said path, each of said roller assemblies including a plurality of roller groups disposed in the adjacent corner portion of said path and arranged longitudinally therealong, each of said roller groups including a plurality of spacedapart rollers mounted for rotation about a common axis extending transversely of said path, the rollers of each roller group being interleaved with the rollers of adjacent roller groups so as to provide a substantially continuous backing wall for the associated strap along the adjacent corner portion of said path, whereby said roller assemblies facilitate the movement of the associated strap along the corner portions of said path to prevent jamming of the associated strap therein.

16. The binder strap track set forth in claim 15, wherein each of said roller groups includes four rollers.

17. The binder strap track set forth in claim 15, wherein the axial position of the rollers is adjustable to enable the rollers of each of said roller groups to be spaced apart a distance less than the width of the associated strap. 1

18. The binder strap track set forth in claim 15, and further including a plurality of parallel roller support plates disposed substantially normal to said axes and spaced apart transversely of said path, each of said roller groups including at least one roller mounted between said adjacent pair of said support plates.

19. The binder strap track set forth in claim 15, and further including two bridging members respectively disposed adjacent the opposite ends of each of said roller assemblies for spanning the gaps between said roller assembly and the adjacent portions of said strap guide, each of said bridging members including a plurality of fingers interleaved with the rollers of the adjacent end one of said roller groups for providing a continuous backing wall for the associated strap between the ends of the roller assemblies and the adjacent straight portions of the path.

20. A binder strap track for guiding a binder strap around an object to bebound, 'said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, said backing wall having a plurality of substantially straight sections interconnected by a plurality of corner sections, a plurality of strap retainer sections respectively mounted adjacent to at least certain of said backing wall sections for movement between retaining positions and releasing positions, said strap retainer sections in the retaining positions thereof cooperating with said backing wall sections to define a path for the associated strap about the location where the object to bebound is positioned, said strap retainer sections in the'releasing positions thereof accommodatingremoval of the associated strap from said path, bias means coupled to each of said strap retainer sections for yieldably urging said strap retainer sections toward the retaining positions thereof with a predetermined force, means for adjustingthe force applied by said bias means to said strap retainer sections, each of at least certain backing wall corner sections comprising a roller assembly including a plurality of rollers disposed in the adjacent portion of said path and arranged longitudinally therealong for facilitating the movement of the associated strap therealong, the associated strap upon tightening about the object to be bound being urged against said strap retainer sections and overcoming the force of said bias means for moving said strap retainer sections to the releasing positions thereof and releasing the associated strap from said path.

21. The binder strap track set forth in claim 20,

wherein said backing wall comprises four straight sections respectively interconnected by four arcuate corner sections, each of said straight sections and the three of said corner sections nearest the point of entry of the associated strap being provided with one of said retainer sections, and further including a pair of side walls respectively disposed adjacent to the opposite side edges of the other of said backing wall corner sections substantially normal thereto and cooperating therewith to define the adjacent portion of said path.

22. A binder strap track for guiding a binder strap from a strapping head around an object to be bound and back to the head, said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, said backing wall having a plurality of substantially straight sections interconnected by a plurality of corner sections, a plurality of strap retainer sections respectively mounted adjacent to said backing wall sections for movement between retaining positions and releasing positions, said strap retainer sectionsin the retaining positions thereof cooperating with said backing wall sections to define a path for the associated strap about the location where the object to be bound is positioned, said strap retainer sections in the releasing positions thereof accommodating removal of the associated strap from said path, severa! of said backing wall sections and said strap retainer sections being dimensioned and arranged to define an entry portion of said path extending from the associated head partly around the object to be bound and having a width substantially greater than the width of the associated strap for accommodating ready passage thereof along said path, the remainder of said backing wall sections and said strap retainer sections being dimensioned and arranged to define a tapered exit portion of said path extending from said entry portion back to the associated head and having a width adjacent to said entry portion substantially equal to the width of said entry portion and having a width adjacent to the associated head only slightly greater than the width of the associated strap for positive and accurate positioning thereof in the associated head, bias means coupled to each of said strap retainer sections for yieldably urging said strap retainer sections toward the retaining positions thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainer sections, each of at least certain backing wall corner sections comprising a roller assembly including a plurality of rollers disposed in the adjacent portion of said path and arranged longitudinally therealong for facilitating the movement of the associated strap therealong, the associated strap upon tightening about the object to be bound being urged against said strap retainer sections and overcoming the force of said bias means for moving said strap retainer sections to the releasing positions thereof and releasing the associated strap from said path.

23. The binder strap track set forth in claim 22, wherein said path is generally rectangular in shape having four straight sections interconnected by four arcuate comer sections.

24. The binder strap track set forth in claim 22, wherein said path is generally rectangular in shape having four straight portions interconnected by four arcuate corner portions, said path being disposed in a substantially vertical plane with the straight portions thereof being disposed substantially horizontally and vertically, said tapered exit portion of said path comprising the bottom straight section of said backing wall.

25. The binder strap track set forth in claim 22, wherein the ends of each of said strap retainer sections overlap the adjacent ends of adjacent strap retainer sections to accommodate free movement of the associated strap in one direction along said path. 

1. A binder strap track for guiding a strap around an object to be bound, said track comprising a pair of strap retainers extending substantially about the location where the object to be bound is positioned and movable between retaining positions and releasing positions, said strap retainers in the retaining positions thereof cooperating to define a path for the associated strap about the location where the object to be bound is positioned, said strap retainers in the releasing positions thereof accommodating removal of the associated strap from said path, bias means coupled to said strap retainers for yieldably urging said strap retainers toward the retaining positions thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainers, the associated strap upon tightening about the object to be bound being urged against said strap retainers and overcoming the force of said bias means for moving said strap retainers to the releasing positions thereof and releasing the associated strap from said path.
 2. The binder strap track set forth in claim 1, wherein said bias means comprises a spring.
 3. The binder strap track set forth in claim 1, wherein said strap retainers are adjustable to be spaced apart in the retaining positions thereof a distance less than the width of the associated strap and in the releasing positions thereof to be spaced apart a distance greater than the width of the associated strap.
 4. The binder strap set forth in claim 1, wherein said path is disposed in a substantially vertical plane.
 5. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, a strap retainer mounted adjacent to said backing wall for movement between a retaining position and a releasing position, said strap retainer in the retaining position thereof cooperating with said backing wall to define a path for the associated strap about the location where the object to be bound is positioned, said strap retainer in the releasing position thereof accommodating removal of the associated strap from said path, bias means coupled to said strap retainer for yieldably urging said strap retainer toward the retaining position thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainer, the associated strap upon tightening about the object to be bound being urged against said strap retainer and overcoming the force of said bias means for moving said strap retainer to the releasing position thereof and releasing the associated strap from said path.
 6. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a backing wall extending substantially about the location where the object to the bound is positioned, a pair of strap retainers respectively mounted adjacent to opposite side edges of said backing wall for movement between retaining positions and releasing positions, said strap retainers in the retaining positions thereof cooperating with each other and with said backing wall to define a path for the associated binder strap about the location where the object to be bound is positioned, said strap retainers in the releasing positions thereof accommodating removal of the associated strap from said path, bias means coupled to each of said strap retainers for yieldably urging said strap retainers toward the retaining positions thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainers, The associated strap upon tightening about the object to be bound being urged against said retaining members and overcoming the force of said bias means for moving said strap retainers to the releasing position thereof and releasing the associated strap from said path.
 7. The binder strap set forth in claim 6, wherein each of said strap retainers comprises a generally L-shaped plate having first and second integral flanges disposed substantially normal to each other, said first flanges being disposed substantially normal to said backing wall when said strap retainers are in the retaining positions thereof, said second flanges being disposed substantially parallel to said backing wall and spaced therefrom and extending toward each other when said strap retainers are in the retaining positions thereof.
 8. The binder strap track set forth in claim 7, wherein said bias means is coupled to said first flanges.
 9. The binder strap track set forth in claim 6, wherein each of said strap retainers comprises a plurality of interconnected sections, the sections of one of said strap retainers corresponding respectively to the sections of the other of said strap retainers to form a plurality of pairs of strap retainer sections, and further including a plurality of bias means respectively coupled to said pairs of strap retainer sections.
 10. The binder strap track set forth in claim 9, wherein the ends of each of said strap retainer sections overlap the adjacent ends of adjacent strap retainer sections to accommodate free movement of the associated strap in one direction along said path.
 11. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, a strap retainer mounted adjacent to said backing wall for pivotal movement about an axis between a retaining position and a releasing position, said strap retainer in the retaining position thereof cooperating with said backing wall to define a path about the location where the object to be bound is positioned, said strap retainer in the releasing position thereof accommodating removal of the associated strap from said path, said strap retainer being provided with a plurality of coupling locations respectively disposed at varying distances from said axis, bias means coupled to said strap retainer at a selected one of said coupling locations for yieldably urging said strap retainer toward the retaining position thereof with a force determined by the distance of the selected coupling location from said axis, the associated strap upon tightening about the object to be bound being urged against said strap retainer and overcoming the force of said bias means for moving said strap retainer to the releasing position thereof and releasing the associated strap from said path.
 12. The binder strap track set forth in claim 11, wherein said bias means comprises a spring.
 13. The binder strap track set forth in claim 11, wherein said strap retainer is provided with an opening therein at each of said coupling locations, said bias means comprising a spring having one end thereof received in a selected one of said openings for engagement with said strap retainer thereat.
 14. The binder strap track set forth in claim 11, wherein said coupling locations are arranged in a generally circular pattern on said strap retainer, said strap retainer being provided with a plurality of first openings therein respectively disposed at said coupling locations and a second opening disposed centrally of said first openings, said bias means comprising a spring having a hook at one end thereof disposed through said second opening and a selected one of said first openings for coupling said spring to said strap retainer.
 15. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a strap guide defining a path for the associated strap extending substantially abouT the location where the object to be bound is positioned, said path having a plurality of substantially straight portions interconnected by a plurality of corner portions, a plurality of roller assemblies respectively mounted on said strap guide adjacent to at least certain corner portions of said path, each of said roller assemblies including a plurality of roller groups disposed in the adjacent corner portion of said path and arranged longitudinally therealong, each of said roller groups including a plurality of spaced-apart rollers mounted for rotation about a common axis extending transversely of said path, the rollers of each roller group being interleaved with the rollers of adjacent roller groups so as to provide a substantially continuous backing wall for the associated strap along the adjacent corner portion of said path, whereby said roller assemblies facilitate the movement of the associated strap along the corner portions of said path to prevent jamming of the associated strap therein.
 16. The binder strap track set forth in claim 15, wherein each of said roller groups includes four rollers.
 17. The binder strap track set forth in claim 15, wherein the axial position of the rollers is adjustable to enable the rollers of each of said roller groups to be spaced apart a distance less than the width of the associated strap.
 18. The binder strap track set forth in claim 15, and further including a plurality of parallel roller support plates disposed substantially normal to said axes and spaced apart transversely of said path, each of said roller groups including at least one roller mounted between said adjacent pair of said support plates.
 19. The binder strap track set forth in claim 15, and further including two bridging members respectively disposed adjacent the opposite ends of each of said roller assemblies for spanning the gaps between said roller assembly and the adjacent portions of said strap guide, each of said bridging members including a plurality of fingers interleaved with the rollers of the adjacent end one of said roller groups for providing a continuous backing wall for the associated strap between the ends of the roller assemblies and the adjacent straight portions of the path.
 20. A binder strap track for guiding a binder strap around an object to be bound, said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, said backing wall having a plurality of substantially straight sections interconnected by a plurality of corner sections, a plurality of strap retainer sections respectively mounted adjacent to at least certain of said backing wall sections for movement between retaining positions and releasing positions, said strap retainer sections in the retaining positions thereof cooperating with said backing wall sections to define a path for the associated strap about the location where the object to be bound is positioned, said strap retainer sections in the releasing positions thereof accommodating removal of the associated strap from said path, bias means coupled to each of said strap retainer sections for yieldably urging said strap retainer sections toward the retaining positions thereof with a predetermined force, means for adjusting the force applied by said bias means to said strap retainer sections, each of at least certain backing wall corner sections comprising a roller assembly including a plurality of rollers disposed in the adjacent portion of said path and arranged longitudinally therealong for facilitating the movement of the associated strap therealong, the associated strap upon tightening about the object to be bound being urged against said strap retainer sections and overcoming the force of said bias means for moving said strap retainer sections to the releasing positions thereof and releasing the associated strap from said path.
 21. The binder strap track set forth in claim 20, wherein said backing wall comprises four straight sections respectivEly interconnected by four arcuate corner sections, each of said straight sections and the three of said corner sections nearest the point of entry of the associated strap being provided with one of said retainer sections, and further including a pair of side walls respectively disposed adjacent to the opposite side edges of the other of said backing wall corner sections substantially normal thereto and cooperating therewith to define the adjacent portion of said path.
 22. A binder strap track for guiding a binder strap from a strapping head around an object to be bound and back to the head, said track comprising a backing wall extending substantially about the location where the object to be bound is positioned, said backing wall having a plurality of substantially straight sections interconnected by a plurality of corner sections, a plurality of strap retainer sections respectively mounted adjacent to said backing wall sections for movement between retaining positions and releasing positions, said strap retainer sections in the retaining positions thereof cooperating with said backing wall sections to define a path for the associated strap about the location where the object to be bound is positioned, said strap retainer sections in the releasing positions thereof accommodating removal of the associated strap from said path, several of said backing wall sections and said strap retainer sections being dimensioned and arranged to define an entry portion of said path extending from the associated head partly around the object to be bound and having a width substantially greater than the width of the associated strap for accommodating ready passage thereof along said path, the remainder of said backing wall sections and said strap retainer sections being dimensioned and arranged to define a tapered exit portion of said path extending from said entry portion back to the associated head and having a width adjacent to said entry portion substantially equal to the width of said entry portion and having a width adjacent to the associated head only slightly greater than the width of the associated strap for positive and accurate positioning thereof in the associated head, bias means coupled to each of said strap retainer sections for yieldably urging said strap retainer sections toward the retaining positions thereof with a predetermined force, and means for adjusting the force applied by said bias means to said strap retainer sections, each of at least certain backing wall corner sections comprising a roller assembly including a plurality of rollers disposed in the adjacent portion of said path and arranged longitudinally therealong for facilitating the movement of the associated strap therealong, the associated strap upon tightening about the object to be bound being urged against said strap retainer sections and overcoming the force of said bias means for moving said strap retainer sections to the releasing positions thereof and releasing the associated strap from said path.
 23. The binder strap track set forth in claim 22, wherein said path is generally rectangular in shape having four straight sections interconnected by four arcuate corner sections.
 24. The binder strap track set forth in claim 22, wherein said path is generally rectangular in shape having four straight portions interconnected by four arcuate corner portions, said path being disposed in a substantially vertical plane with the straight portions thereof being disposed substantially horizontally and vertically, said tapered exit portion of said path comprising the bottom straight section of said backing wall.
 25. The binder strap track set forth in claim 22, wherein the ends of each of said strap retainer sections overlap the adjacent ends of adjacent strap retainer sections to accommodate free movement of the associated strap in one direction along said path. 